This is a competitive renewal application for a National Research Service Award (NRSA) Institutional Training grant (T32) for research training in pediatric urology at Children's Hospital Boston. For the past 4 years, this funding mechanism has supported the research component of our pediatric urology fellowship program. The pediatric urology fellowship at Children's Hospital Boston is the oldest and one of the most highly regarded such programs in the world. Since its inception in 1978, the Children's Hospital pediatric urology fellowship program has trained many of the leading academic pediatric urologists now practicing in the United States. Many of these former trainees are now division chiefs or department heads at major academic institutions. The Urology Department at Children's Hospital is one of the world's leading centers for pediatric urology and genitourinary reconstruction and has one of the largest research programs dedicated to basic urology research in the country. The department is home to the Children's Hospital/Harvard Urological Diseases Research Center, a George O'Brien Urology Research Center funded by a P50 grant from the NIDDK (one of 5 O'Brien Urology centers in the country). In the first funding period, the trainees have conducted laboratory-based studies of urogenital tract physiology and pathophysiology during 2 uninterrupted years of the 3-year fellowship. In the next funding period, we will continue this strong focus on basic science research;however, we now will also offer training in epidemiologic studies related to pediatric urology. The overall goals of the program are: (1) to enhance the trainees'understanding of basic mechanisms of cell physiology and the molecular basis of disease;(2) to teach state-of-the-art, hypothesis-driven research methodology;and (3) to provide sufficient time and guidance for a mature postdoctoral experience in basic or translational studies relevant to the trainees'future clinical career and academic leadership roles. The fellowship represents a unique combination of outstanding clinical and basic research training within one of the world's leading centers for academic medicine and biomedical science. It is designed to enable our graduates to establish their own competitive programs of scholarship and research during their careers as academic pediatric urologists. These clinician-scientists can then contribute to understanding the genitourinary system in fundamental terms and to translating basic research findings into clinical applications. The T32 Pediatric Urology Research Training mechanism is the major source of support for the fellows during the 2 continuous research years of their fellowship.